A = reason code
Reason codes are as follows:
SC_BIT ($00) Test for Escape. Returns Fc = 1 if escape has been
pressed, else Fc = 0.
SC_ACK ($01) Acknowledge escape and also flush input buffer.
Fz = 1 if there was no escape to acknowledge, else
Fz = 0. Note that RC_ESC = SC_ACK so you can acknowledge
escape with this call without reloading the accumulator.
This also resets the machine timeout.
SC_SET ($02) Set escape, ie. simulate an escape condition
SC_RES ($03) Reset escape without flushing the input buffer.
SC_TST ($04) Test if escape detection is enabled or disabled. Fc = 0
always, and A = SC_ENA if it is enabled, A = SC_DIS if
it is disabled.
SC_ENA ($05) Enable escape detection
SC_DIS ($06) Disable escape detection.
OUT: if A(in) = SC_BIT then
Fc = 0, no escape
Fc = 1, escape detected
if A(in) = SC_ACK then
Fc = 0,
Fz = 1, no escape
Fz = 0, escape acknowledged, machine timeout reset
if A(in) = SC_TST then
Fc = 0
A = SC_ENA, escape detection enabled
A = SC_DIS, escape detection disabled
other A(in) values
Fc = 0
Registers changed after return:
On entry to an application, Escape detection is always disabled. Application may have to enable it if API with timeout requires escape detection (like OS_Tin, OS_Dly or OS_Si).
GN_Err, display an interactive error box
GN_Esp, return an extended pointer to a system error message
OS_Erc, get error context
OS_Erh, set error handler